Carbon‐tuned cathodoluminescence of semi‐insulating GaN

We report on the cathodoluminescence (CL) of nominally undoped semi‐insulating GaN layers grown by hot‐wall metal‐organic chemical vapor deposition (MOCVD) at a threefold increase of the growth rate limited by the TMGa flow. The growth kinetics is such, that C is the only background impurity in the layers with controllably increasing concentration from 5 × 10 16 to 6 × 10 17  cm −3 , while other background impurities, H, O and Si, are essentially at the SIMS detection levels. The hot‐wall MOCVD is not an ordinary approach to GaN growth process and this study corroborates a more perceptive outlook on the C incorporation in GaN and any potential C‐incorporation‐mediated luminescence, including the observed here blue luminescence (BL) at ∼417 nm, and the yellow luminescence (YL) with shifting peak position towards shorter wavelengths, ∼555–543–525 nm.